Service-Connected Disability Guide
Service connection is the legal link between your military service and your current medical condition. Without it, you can't receive VA disability compensation. There are five types of service connection — understanding which applies to your claim is the first step to a successful rating.
Type 1
Direct Service Connection
The most common type. Your condition started during active duty OR was diagnosed after service but is clearly linked to an in-service event, injury, or disease. Requires: (1) current diagnosis, (2) in-service event, (3) medical nexus linking them.
Key Evidence:Service treatment records showing the condition or incident · Post-service medical diagnosis · Nexus letter from a private doctor stating "at least as likely as not" the condition is service-related
Type 2
Presumptive Service Connection
The VA presumes certain conditions are related to service without requiring a nexus letter. Includes: Agent Orange exposures, Gulf War syndrome, PACT Act burn pit conditions, POW-related conditions, and 50+ chronic diseases appearing within 1 year of discharge.
Key Evidence:Proof of service in the qualifying location or period · Current diagnosis of a presumptive condition · No nexus letter required — the VA accepts the link automatically
Type 3
Secondary Service Connection
Your service-connected condition caused or aggravated a new condition. Example: service-connected knee injury causes hip arthritis from altered gait. The secondary condition gets its own rating. You can chain secondaries (e.g., diabetes → neuropathy → depression).
Key Evidence:Rating decision for the primary service-connected condition · Diagnosis of the secondary condition · Medical opinion linking them causally
Type 4
Aggravation
A pre-existing condition that was made permanently worse by military service. The VA owes you compensation for the portion your service worsened beyond natural progression. Pre-existing conditions noted at MEPS aren't automatically excluded.
Key Evidence:MEPS entry physical documentation · Service treatment records showing worsening · Medical opinion on natural progression vs. service-caused aggravation
Type 5
Lay Evidence / Buddy Statements
Your own statements (personal statements) and statements from fellow servicemembers who observed your condition or incident are legally valid evidence. The VA must consider lay evidence. Buddy statements can establish in-service events when records are missing.
Key Evidence:VA Form 21-4142 personal statement · Buddy letters (VA Form 21-10210) · Unit logs, deployment records, news articles corroborating the event